Comparison of collection methods to determine atmospheric deposition in a rural Mediterranean site (NE Spain)

Izquierdo R., Avila A. (2012) Comparison of collection methods to determine atmospheric deposition in a rural Mediterranean site (NE Spain). Journal of Atmospheric Chemistry. 69: 351-368.
Enllaç
Doi: 10.1007/s10874-012-9246-1

Resum:

Wet-only, dry-only, bulk deposition and deposition of sedimentary particles and gases deposited after the last rain (DAR) were collected weekly at La Castanya station in the Montseny mountains (NE Spain, 41 46′N, 2 21′E) from February 2009 to July 2010. These samples were analysed for pH, alkalinity, and the concentrations of major ions (Cl-, NO 3 -, SO4 2-, Na+, K +, Ca2+, Mg2+, NH4 +). Significant differences were observed between bulk and wet-only precipitation, with an enrichment of ions associated to coarse particles in bulk deposition. The comparison between wet and dry fluxes revealed that the removal of compounds at Montseny occurred mainly by wet deposition, which accounted for 74 % of total deposition. The dry flux was characterised by the predominance of K +, Ca2+ and Mg2+, which are related to coarse particles. Bulk collection methods at Montseny were considered representative of total atmospheric deposition, since bulk deposition plus DAR accounted for 97 % of total deposition measured with wet and dry-only collection devices. Thus, bulk deposition collectors can be recommended for deposition networks at remote sites (lacking electricity connection) in environments, where coarse particles are a predominant fraction of the aerosol mass. © 2013 Springer Science+Business Media Dordrecht.

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Trajectory statistical analysis of atmospheric transport patterns and trends in precipitation chemistry of a rural site in NE Spain in 1984-2009

Izquierdo R., Avila A., Alarcón M. (2012) Trajectory statistical analysis of atmospheric transport patterns and trends in precipitation chemistry of a rural site in NE Spain in 1984-2009. Atmospheric Environment. 61: 400-408.
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Doi: 10.1016/j.atmosenv.2012.07.060

Resum:

The aim of this study is to interpret the variation of precipitation chemistry during the last 25 years in Montseny (NE Spain) by taking into account the main air mass transport routes and emission sources. To this end, trajectory cluster analysis and source-receptor models were applied to an early monitoring period (1984-1993) and compared to a more recent one (1998-2009). A decrease of Atlantic advections and increase of African and European air flows was found. Cluster analysis and source-receptor approaches showed that this region is under the influence of natural and anthropogenic sources from the local and long-range scale. Sulphate and H + source areas extended over a vast stretch of central Europe in the early period, but were drastically reduced in the recent period, showing the effectiveness of pollution abatement measures for S. On the other hand, NO 3 - sources areas from central Europe strikingly increased. Ship emissions and industrialisation in Eastern Europe and North Africa seem to be acquiring a greater role in the recent period. © 2012 Elsevier Ltd.

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Atmospheric phosphorus deposition in a near-coastal rural site in the NE Iberian Peninsula and its role in marine productivity

Izquierdo R., Benítez-Nelson C.R., Masqué P., Castillo S., Alastuey A., Àvila A. (2012) Atmospheric phosphorus deposition in a near-coastal rural site in the NE Iberian Peninsula and its role in marine productivity. Atmospheric Environment. 49: 361-370.
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Doi: 10.1016/j.atmosenv.2011.11.007

Resum:

In this study, African red-rains were collected at Montseny (NE Spain) on a weekly basis and analyzed for total particulate phosphorus (TPP), total dissolved P (TDP) and soluble reactive P (SRP) for the period 1996-2008. Wet and dry weekly deposition of TPP was analyzed for all provenances in 2002-2003. In this period, African sources were found to contribute 66% of the 576μmolm -2y -1 of total particulate phosphorus (TPP) deposited in Montseny, split almost evenly between dry and wet deposition. Measurement of this dry deposition further allowed a direct determination of deposition velocity (V d), which suggested significant depositional differences between African (V d=3.1±0.80cms -1) and non-African events (V d=1.07±0.13cms -1). Measurement of TDP concentrations during the African rains suggests a solubility of 11.2% TPP. SRP solubility was lower (2.2%), highlighting the importance of understanding the composition of the atmospherically derived P component. Samples were collected 25km from the Mediterranean coast and were assumed to represent the atmospheric P input to coastal waters. On an annual basis, atmospheric-derived soluble P contributed <1% of annual new primary production in the western Mediterranean. However, one strong African dust event (22-27 May, 2008) accounted for 24-33 % of the atmospheric P-induced annual new production. These results highlight the potential biogeochemical importance of seasonality, source, and composition of aerosols deposited in the Western Mediterranean Sea. © 2011 Elsevier Ltd.

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Changes in atmospheric deposition and streamwater chemistry over 25years in undisturbed catchments in a Mediterranean mountain environment

Àvila A., Rodà F. (2012) Changes in atmospheric deposition and streamwater chemistry over 25years in undisturbed catchments in a Mediterranean mountain environment. Science of the Total Environment. 434: 18-27.
Enllaç
Doi: 10.1016/j.scitotenv.2011.11.062

Resum:

Surface water chemistry has changed in response to reduced atmospheric deposition of sulphur and acidity in many regions of Europe and North America. Most of these studies come from acidic or low-alkalinity surface waters under high acidic deposition. Mediterranean climates offer a different biogeochemical context, characterised by streamwaters of higher alkalinity and low acid inputs. In this paper, we use surveys of streamwater chemistry conducted in 1981-1984 and again in 2007 in the Montseny natural park (NE Spain) to test whether streamwaters of these well-buffered catchments respond to changes in atmospheric deposition, which has declined for S during the last decades in NE Spain while remaining about stable for nitrogen. The 23 sampled streams drained heathland, beech forests and evergreen oak forests in relatively undisturbed small catchments underlain by silicate bedrock. Bulk deposition of sulphate at Montseny decreased by 54% while nitrate bulk deposition increased (non-significantly) by 30% in this period. Total N deposition is estimated in the range 15-30kg Nha-1y-1 for NE Spain. This is well above threshold values (e.g. 10kg Nha-1y-1) reported as starting nitrogen saturation symptoms in forest ecosystems in Europe. Baseflow sulphate concentrations decreased on average by 47μeqL-1 or 29% of early 1980s concentrations. Baseflow mean nitrate concentrations increased significantly but only from 5.5 to 8.9μeqL-1. Thus, despite decades of high N deposition, these ecosystems appear to be still far from N saturation. Baseflow alkalinity and base cation concentrations increased substantially, probably a combined result of decreased S deposition, enhanced silicate weathering under current higher temperatures, reduced plant cation uptake as vegetation matures, and slightly drier conditions in the survey of 2007. Overall, these well-buffered catchments have shown sizable changes in baseflow chemistry in response to changed atmospheric deposition and other environmental changes. © 2011 Elsevier B.V.

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